Chapter XIII The Continuous Cultivation of Micro-organisms

Evans, Celia G.; Herbert, D.; Tempest, D. W.

doi:10.1016/s0580-9517(08)70227-7

Cited by 240 publications

(74 citation statements)

References 9 publications

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“…For MB37, an additional duplicate was performed in addition to the previously performed triplicate (7), and the averaged quintuplicate data set was used for this report. A defined simple salts medium, described previously (16), with nitrilotriacetic acid (2 mM) rather than citrate as a chelator was used.…”

Section: Methodsmentioning

confidence: 99%

Uncoupling of Substrate-Level Phosphorylation in Escherichia coli during Glucose-Limited Growth

Sharma

Hellingwerf

Mattos

et al. 2012

Appl Environ Microbiol

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ABSTRACTThe respiratory chain ofEscherichia colicontains three different cytochrome oxidases. Whereas the cytochromebooxidase and the cytochromebd-I oxidase are well characterized and have been shown to contribute to proton translocation, physiological data suggested a nonelectrogenic functioning of the cytochromebd-II oxidase. Recently, however, this view was challenged by anin vitrobiochemical analysis that showed that the activity of cytochromebd-II oxidase does contribute to proton translocation with an H+/e−stoichiometry of 1. Here, we propose that this apparent discrepancy is due to the activities of two alternative catabolic pathways: the pyruvate oxidase pathway for acetate production and a pathway with methylglyoxal as an intermediate for the production of lactate. The ATP yields of these pathways are lower than those of the pathways that have so far always been assumed to catalyze the main catabolic flux under energy-limited growth conditions (i.e., pyruvate dehydrogenase and lactate dehydrogenase). Inclusion of these alternative pathways in the flux analysis of growingE. colistrains for the calculation of the catabolic ATP synthesis rate indicates an electrogenic function of the cytochromebd-II oxidase, compatible with an H+/e−ratio of 1. This analysis shows for the first time the extent of bypassing of substrate-level phosphorylation inE. coliunder energy-limited growth conditions.

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Section: Methodsmentioning

confidence: 99%

Uncoupling of Substrate-Level Phosphorylation in Escherichia coli during Glucose-Limited Growth

Sharma

Hellingwerf

Mattos

et al. 2012

Appl Environ Microbiol

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“…Cells were grown at 378C in a defined minimal mineral medium containing 55 mM glucose 11 with a pH of 7.0 and a buffer of 15.6 g/L Na 2 H 2 PO 4 . Media were autoclaved for 20 minutes at 1208C, with the exception of glucose (10 minutes, 1108C).…”

Section: Methodsmentioning

confidence: 99%

De Novo Acquisition of Resistance to Three Antibiotics by Escherichia coli

Horst

Schuurmans

Smid

et al. 2011

Microbial Drug Resistance

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General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The acquisition of resistance to amoxicillin, tetracycline, and enrofloxacin by Escherichia coli MG 1655 was examined by exposing growing cells to constant or stepwise increasing concentrations of these compounds. The minimal inhibitory concentration (MIC) of E. coli for amoxicillin increased from 4-8 to 32 mg/ml after growth in the presence of 1.25 or 2.5 mg/ml. By stepwise increasing the exposure, an MIC of 512 mg/ml was reached. This high MIC was maintained after removal of the antibiotics, whereas the lesser increase after exposure to low levels was reversed, indicating that the high MIC was due to a genetic change, but the lower one to phenotypic adaptation only. The MIC for tetracycline increased from 2 mg/ml to maximally 32 mg/ml. The MIC decreased to control levels in the absence of tetracycline, so no genetic changes seem to have occurred. The MIC for enrofloxacin increased from 0.25 mg/ml to maximally 512 mg/ml depending on the concentration during growth. These data mostly support the ''radical-based'' theory that bactericidal antibiotics induce a common mechanism that contributes to cell killing. Our findings indicate that exposure to low levels of antibiotics causes an increase in MIC above the concentration that the cells were exposed to. The implication is that exposure to low levels of antibiotics should be prevented as much as possible, because this causes resistance far more than high concentrations that inhibit growth or kill the cell and thus prevent acquisition of resistance.

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“…Cells were grown in Applikon-type fermentors (1-3, 10) at a dilution rate of 0.15 Ϯ 0.01 h Ϫ1 under glucose-limited conditions. A simple salts medium described by Evans et al (10) was used, but instead of citrate, nitriloacetic acid (2 mM) was used as the chelator. Selenite (30 g/liter) and thiamine (15 mg/liter) were added to the medium.…”

Section: Vol 192 2010 Both Quinone Pools Of E Coli Regulate Arcb 747mentioning

confidence: 99%

“…Detection of the quinones was performed at 290 nm for ubiquinones and at 248 nm for menaquinones. The amount of each quinone species was calculated from the relevant peak area, using ubiquinone-10 (UQ 10 ) and menaquinone-4 as standards and the method described by Shestopalov et al (37). The methanol, ethanol, and petroleum ether used were analytical grade.…”

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confidence: 99%

The ArcBA Two-Component System of Escherichia coli Is Regulated by the Redox State of both the Ubiquinone and the Menaquinone Pool

et al. 2010

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ArcBA is a two-component regulatory system of Escherichia coli involved in sensing oxygen availability and the concomitant transcriptional regulation of oxidative and fermentative catabolism. Based on in vitro data, it has been postulated that the redox state of the ubiquinone pool is the determinant for ArcB kinase activity. Here we report on the in vivo regulation of ArcB activation, as determined using a lacZ reporter specifically responsive to phosphorylated ArcA. Our results indicate that upon deletion of a ubiquinone biosynthetic enzyme, regulation of ArcB in the anaerobic-aerobic transition is not affected. In contrast, interference with menaquinone biosynthesis leads to inactivation of ArcB during anaerobic growth; this phenotype is fully rescued by addition of a menaquinone precursor. This clearly demonstrates that the menaquinones play a major role in ArcB activation. ArcB shows a complex pattern of regulation when E. coli is titrated through the entire aerobiosis range; ArcB is activated under anaerobic and subaerobic conditions and is much less active under fully aerobic and microaerobic conditions. Furthermore, there is no correlation between ArcB activation and the redox state of the ubiquinone pool, but there is a restricted correlation between the total cellular ubiquinone content and ArcB activity due to the considerable increase in the size of the ubiquinone pool with increasing degrees of aerobiosis. These results lead to the working hypothesis that the in vivo activity of ArcB in E. coli is modulated by the redox state of the menaquinone pool and that the ubiquinone/ubiquinol ratio in vivo surely is not the only determinant of ArcB activity.

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Chapter XIII The Continuous Cultivation of Micro-organisms

Cited by 240 publications

References 9 publications

Uncoupling of Substrate-Level Phosphorylation in Escherichia coli during Glucose-Limited Growth

Uncoupling of Substrate-Level Phosphorylation in Escherichia coli during Glucose-Limited Growth

De Novo Acquisition of Resistance to Three Antibiotics by Escherichia coli

The ArcBA Two-Component System of Escherichia coli Is Regulated by the Redox State of both the Ubiquinone and the Menaquinone Pool

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